Using Reactive Attachables

What are they for?

Attachables are simply a way to attach post-initialization initialization to components in a way that applies generically to different types of components. For example:

new Layout() {
    Children = {
        new EditorImage() {
            Source = "https://picsum.photos/300"
        }
        .Attach<ColorSOAttachable>("Button/Background/Normal"),
        new EditorLabel() {
            Text = "Hello, World!"
        }
        .Attach<FontAttachable>()
        .Attach<ColorSOAttachable>("Button/Text/Normal")
    }
};

Both images and colors can have a ColorSO made available to them, so we can use the same attachable for both. This allows us to create a generic attachable that can be used for any component that has a ColorSO property.